1. Field of the Invention
The present invention relates to an apparatus, method and computer program, for rotating, moving, scaling up or down or otherwise manipulating a three-dimensional object on a display screen by a touch-operated input device.
This application claims the priority of the Japanese Patent Application No. 2003-050093 filed on Feb. 26, 2003, the entirety of which is incorporated by reference herein.
2. Description of the Related Art
Generally, a pointing device such as a mouse or the like is used to rotate, move, scale up or down or otherwise manipulate a three-dimensional object displayed on a display screen. With the pointing device like the mouse, the user can intuitively make a pointing operation with a high degree of freedom because a movement of the user's hand or finger precisely results in a movement of a pointing cursor on the display screen.
However, the pointing device such as a mouse can only be used smoothly and comfortably in an ample operating space. There will arise no problem with a pointing device which is used with an apparatus to which a variety of peripheral devices is to be connected, such as a personal computer or the like. But the pointing device is not suitable for use with a portable information device such as a mobile phone or PDA (portable digital assistant) as well as with a portable electronic appliance such as digital video camcorder (=camera/recorder) or the like.
Many of recent portable electronic appliances such as the portable phone, PDA, digital video camcorder, etc. have installed therein a touch-operated input device like a touch-sensor panel as an input device to enable the user to select an object such as an icon or the like in a menu screen.
The touch-operated input device is disposed opposite to the display screen. When the user touches, by the fingertip or a pen, directly an arbitrary position on the display screen of the touch-operated input device, the touch-operated input device can detect the coordinate of the user-touched position and provide an event equal to that provided by the mouse, such as click or double click. There have been proposed various types of touch-operated input devices such as an analog capacitive-coupling type, resistive membrane type and the like. Since the touch-operated input device can be incorporated directly in a display unit, it does not need any operating space which would be required for operation of a mouse. Namely, the input device of this type can be said to be suitable for use with the above-mentioned portable electronic appliance.
The well-known techniques for manipulating a three-dimensional object displayed on a display screen, for example, rotating it, by the touch-operated input device include a method of defining an axis and angle of rotation by defining, by a tablet, a coordinate on the surface of a semitransparent ball displayed on a three-dimensional object, for example (as disclosed in the Japanese Published Unexamined Patent Application No. 1993-290146, paragraphs 0009 and 0010, for example), a technique for converting a movement of a position of contact on a spherical surface into an angle of rotation of a three-dimensional object by the use of a spherical or cylindrical sensor capable of detecting the position of contact on the spherical surface (as disclosed in the Japanese Published Unexamined Patent Application No. 1995-5980, for example), etc.
However, if any of the above-mentioned well-known techniques is applied in a portable electronic appliance such as a portable phone, PDA, digital video camcorder or the like for viewing any other aspect of a three-dimensional object, or moving a three-dimensional object to another on-screen position or scaling it down because it is obstructive on the display screen, for example, the electronic appliance will be complicated in construction and thus difficult to operate. That is, such an electronic appliance is not appropriate for ordinary users.